Alternating-current regulator.



E. F. GEHRKENS.

ALTERNATING CURRENT REGULATOR.

Patented Jan. 16, 1912..

APPLIOATIQN FILED MAR. 2, 1910.

lnvenflor Edward F. Gehrkens,

ntnesses:

His Attorney,

UNITED STATES PATENT o Fron.

EDWARD F. GEHRKENS, 0F PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ALTERNATINGEGURRENT REOULATOR.

Specification of Letters Patent.

Patented Jan. 16, 1912.

Application filed March 2, 1910. Serial No. 54 ,947.

To 1177 whom it may concern:

Be it known that I, EDWARD F. GEHRKENs. a citizen of the United States,residing at Pittsfield, county of Berkshire, State of Massachusetts,have invented certain new and useful Improvements in Alternating-Current Regulators, of which the following is a specification.

This invention relates to apparatus for controlling thevoltage of atransformer, in such manner thata transformer may be operated through aconsiderable range of voltage with a constant output or a constantsecondary current. The control is effected by cutting outor insuccessive sections of the primary winding.

The object of the invention is to effect this operation smoothly andgradually, without any sudden change in voltage when a section is cutout or inserted in circuit.

In accordance with the provisions of the patent statutes, I shallhereinafter explain the best mode in which I have contemplated applyingthe principle of my invention in an actual embodiment thereof. Theparticular embodiment which I shall describe and illustrate but to whichI do not limit myself comprises in general the followinginstrumentalities, the novel features of my invention being pointed outwith particularity in the claims annexed to and made a part of thisspecification.

a. A transformer with taps in the primary and a secondary which may bearranged for a series parallel connection, as, I have illustrated, or,may be a simple secondary wind- A switch for connecting the secondarywinding in series or in parallel. WVhile l have illustrated this switch,it will obviously not be necessary for a simple secondary wind- 1n 5.Two dial switches for changing the tap connections of the primarywinding.

(Z; A switch or switches for disconnecting groups of sections after theyhave been cut out by the aforesaid dial switches.

e. A compensator whose winding is subdivided into a number of equalsections; the terminals of said compensator being respec tivelyconnected permanently to the moving arms or switch blades of the twodial switches.

I f. A set of parallel contact bars respectively connected to taps ledout from the subdivisions of the com ensator.

g. A set of parallel co lector bars arranged at right angles to thecontact bars, and having individual resistances connected to them and toa common conductor leading to one side of the power circuit; the otherside of said circuit being connected to one end of the primary windingof the transformer.

h. A movable switch member consisting of a plurality of contact fingersinsulated from each other and mounted on a common carrier, said fingersbeing long enough .to bear at one end always on their respectivecollector bars, and at their other ends on one or another of the contactbars according to the position to which they may be moved by thecarrier.

2'. A two-part commutator controlling .a contactor switch in series withthe compensator winding, and by means of which the circuit of saidwinding can be opened.

j. A potential transformer may also be connected with the power circuitsupplying current to a rheostat and a voltmeter; said rheostat beingoperated synchronously with the dial switches, as I have shown. This,however, is not necessary to my invention.

in. An operating motor,shafts and gearing for actuating the dialswitches, the disconthe drawing, though this number is immaterial. Thesecondary winding 3 is also divided into sections, preferably two innumher; which by means of a switch e can be two sets of clips arearranged concentric with a shaft 8 on which are mounted -two switch armsor blades 9, 10, the former angularly in advance of the latter and eachcooperating with its respective set of clips. The head of each blade islong enough and the spacing of the clipsis such that each blade remainsin contact with each clip during the time necessary for the compensatorswitch to travel over all of the contact bars in both directions. 1

The shaft 8 is driven by a motor'll controlled by a reversing switch 11or a limit switch 11; The motor is connected with 1 the shaft byintermittent gearing; such for example as the wheel 12 containingnotches separated by wide teeth with concave ends to fit the peripheryof the pinion 13 between its two opposite teeth, whereby the'wheel' 12will be moved forward one tooth fer each half revolution of the pinion,and will be locked against rotation during the time ela'psing betweentwo actuations. The p nion 13 is carried on a counter shaft 14 which isalso provided with a worm gear 15 driven by a worm 16 ona short countershaft haw ing a spur gear 17 meshing with a plnion I 18 on the motorshaft.- This train of gearing sential point being thatthecounter shaftis merely illustrative and may be varied to meet the wishes of theconstructor; the es- 14 shall make one-half revolution between twoactuations of the shaft 8.

At each actuation of the shaft 8 one of 'the sections of the primarywinding ofthe transformer is cut out orin, depending upon the directionin which the motor is revolving. The switch blades 9, 10 are so set thatwhen one is just about'to move from one clip to the next, theother hasjust engaged a clip, and during the movement of the first blade toanother clip, the second blade slides along its clip in constant contacttherewith. It thus appears that the sections of the primary winding arenever entirely open cir cuited by the dial switches during their Imovement. In order, however, to prevent the terminals of the windingfrom being subjected to excessive voltages, provision is made fordisconnect-mg a certain number of sections after they have been cut outby the dial switches. In t-hedra'wing, the first" four sections and thesecond four can thus" be disconnected in succession, by means of therotary switches 19, 20, each comprising a contact segment 21 adapted toconnect the two fingers 22 in circuit with the ends of the adjacentsections of the primary winding.

The length of each segment is such that it will cease to bridge thesefingers after the.

four sections which it controls have been cut out by the switch blades9, 10. These blades are connected by conductors 23 with the terminals ofa compensator 24, whose winding is divided into sections from which tapsare led to contact bars 25 arranged parallel with and insulated fromeach other. In the drawing I have shown seven bars, but in practice thisnumber is increased to double that number or even more, in order tosecure as fine a subdivision of the changes of voltage as possible. Inproximity to the contact bars, but at right angles thereto, are severalinsulated collector strips 26. In practice,

these strips take the form of rings mounted on a drum, on which are alsocarriedthe Connected with each colthe fingers are-stepped in theirarrangement,

as shown, so that they do not part from a contact bar all at the sameinstant, but one after the other, the leading finger making contact withthe next bar before the trailing finger has left the former bar. As thecarrier draws the fingersover the compensator contact bars, the sectionsof the compensator are cut out oneafter-the other,'unt1l finally all thefingers rest on the end bar.- In order to accommodate all the. fingers,the end bars are made wider than the intermediate ones; as shown." & Anysuitable gearing may be adopted for moving the carrier in synchronismwith the dial switches; but I- prefer to provide the carrier with a rack31 meshin with a sector gear 32 which can be oscillated by a connectingrod 33 pivoted to a crank 34 on the end of the counter shaft-14. Thecrank is so set that it passes its dead centers at the times when thepinion 13 is actuating the wheel 12, and the fingers are resting uponthe end bars of the compensator; In serieswiththe' coils of thecompensator is an electromagnetic switch '35, preferably ofthe-contactor type,"whose coil 36 is connected to a supply circuit 37through a. circuit breaker orcommutator 38 operated by the counter shaft14 in "synchronism with the intermittent gearing. When this contactor isdeline'rgized, it opens the compensator winding, thereby breaking thecircuit from the primary winding of the transformer through thecompensator. This takes place as soon as all the fingers of thecompensator switch are on either of the wide end bars, and before theblade of either dial switch has opened the circuit. \Vith thisarrangement, no current is broken by either of the dial switches, butonly by the contactor, whose contacts can be readily renewed if theyburn out. compensator switch can be reduced to a minimum by having alarge number of taps on the compensator. thereby reducing the voltagebetween the taps to a very small amount, and also by having a largenumber of fingers, so that there will be practically nobreaking ofcurrent but. rather a gradual 'shiftingdue to the gradually variedresist-- ances between the compensator taps, said resistances having asufiicient capacity to permit the compensator to be left in anyposition.

\Vhen the higli tension power circuit is connected across the entireprimary winding of thetransformer, the minimum voltage will be deliveredby the secondary winding.

This is obtained when the blade 9 is on the clip a and the fingers ofthe compensator switch rest on the left hand end bar 25, as shown in thedrawing. Itwill be noticed that the blade 10 is also in contact with theclip 7), but practically no current will flow through the switch 7,owing to the interposition of the compensator coils. The continuedrotation of' the motor causes the carrier to traverse the contact bars25, gradually cutting outthe compensator coils, until the fingers reston the right hand end bar, and the line is then in effect connecteddirectly to the clip I) and the first section of the primary winding iscut out. At this point, the

5 intermittent gearing operates, moving the blade 5) to the clip a, theblade 10 still remaining on the clip I). This reverses the polarity ofthe compensator, so that the reverse movement of the carrier which isnow effected by the next half revolution of the crank proceedsto cut outthe coils of the compensator from between the clips 7) and 1;; thusagain gradually increasing the voltage of the secondary of thetransformer.

This alternating movement of the blades 9, 1'.) and the intermittentmovement of the compensator switch are continued until the entire rangeof voltage has been covered, or until such a voltagerhztslieen reachedas is desired. By this-arrangement a continuous movement of theactuating shaft produces a uniform rarige of voltage, and i passing fromone" tap to another of the primary winding an independent adjustment ofthe, compensator ta psis not required; b ut this The burning of thecontacts of the'i adjustment is automatic and dependent upon. the shaftactuating the dial switch blade It will be obvious that while I haveillustrated the actuating shaft as driven by a motor that this shaft ifdesired may be operated by hand, or by other suitable means.

\Vith the secondary coils in multiple, the range in the secondaryvoltage of the transformer, for a complete range of operation of thedial switches, is from 40 to 100 volts, assuming that the apparatus iscapable of a range of from .40 to 200 volts man. To obtain a highervoltage than 100 it is necessary to open the circuit of the entireswitching apparatus, so as to disconnect it from thepower circuit, andthen connect the sections of the secondary winding in series by means ofthe switch 4. This arrangement will produce a higher voltage across thesecondary winding than was previously obtained, and in order to preventtoo sudden it change, the primary switching apparatus must be run backenough to secure the same voltage as before the change Was made in theconnections of the secondary. This rearrangement of the dial switchesmust be made before they are again connected to the power circuit, andin order to enable the operator to determine the proper adjustment avoltage indicator is provided, which will show at all times what thevoltage of the secondary circuit is, whether the transformer is inservice or not. The preferred form of indicator is a voltmeter 39connected to the secondary 40 of a small potential transformer whoseprimary 41 is across the power mains. This transformer has a doublewinding, each of 100 volts, arranged as shown in the drawing, and bymeans of a switch 42, preferably mechanically connected with theseries-parallel switch 4 for the secondary of the main transformer,either the full voltage or the half voltage of the potential transformercan be thrown upon the voltmeter; the former when the secondary isconnected in series and the latter when it is connected in parallel. Thecurrent from the potential transformer passes through a rheostat 4?,whose switch arm 44 is mechanically operated by the shaft 8, as by meansof sprockets and an endless belt 45. The resistance is such that as thearm moves over the buttons of the rheostat the voltmeter will showapproximately the. voltage of the secondary winding of the maintransformer.-

In actual practice, this invention has given entire satisfaction with atransformer capable of delivering 1(300 kilo-watts, the line voltagebeing 2200, and the secondary voltage varying between 40 and 200; theamperes varying correspondiugly 50000 to 8000. The voltmeter shows a perfectly smooth regulation, the etliciency and from ' power factor of theinstallation are improved, and the apparatus is found tobe especiallyadapted for use with single phase low voltage transformers having largecurrent capacity.

While I have described the disconnecting of a certain number of sectionsof the transformer winding from the remainder to prevent danger to thewinding from excessive voltages, I do not claim this invention which isclaimed in a copending application of Walter S. Moody, Serial Number546,946, filed March 2, 1910.

A preferred embodiment of my invention has been described in the abovespecificatio'n. I do not limit myself to this embodiment, however, butseek in the appended claims to cover'all embodiments which will beobvious to those skilled in the art, and within the scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

-1. The combination with a transformer having its primary windingdivided into sections and connected at one end with one of the supplymains, of two switches controlling alternate sections -of said winding,a compensator having its terminals connected respectively to the movingmembers of said switches, means for actuating said members, a connectionto the other supply main, and means dependent upon said actuating meansfor shifting said connection from end to end of said. compensator.

2. The combination with a transformer having its primary winding dividedinto sections, of two switches each having stationary contacts connectedto alternate sections, a movable member for each switch, means foractuating said members, a subdivided compensator having its terminalsconnected respectively to said members, contacts connected with thedivisions of said compensator, a movable switch cooperating with saidcontacts, and means operating said switch dependent upon said actuatingmeans. I

3. The combination with a transformer having its primary winding dividedinto sect-ions, of two dial switches having their clips connected toalternatesections, a subdivided compensator' having its terminalsconnected to the movable blades of said switches, contact bars connectedin between the divisions of the compensator, and a carrier provided witha plurality of stepped fingers adapted to trawerse said bars.-

4. The combination with a transformer having its primary winding dividedinto Sections, of two dial switches having their clips connected toalternate sections, a subdlvided compensator havmgnts terminalsconnectedto the movable blades of said switches, contact bars connectedin bet-ween the d visions of the compensator, a carrier provided with aplurality of stepped fingers adapted to traverse said bars, and meansfor intermittently moving said switch .blades when said fingers rest onthe end bars.

5. The combination with a transformer having its primary winding dividedinto sections,- of two dial switches having their. clips connected toalternate sections, a common shaft for the blades of saidswitches, asubdivided compensator in circuit with said blades, a switch cooperatingwith the coils of said compensator, a shaft for actuating saidcompensator switch, and intermittent gearing between said shaft will theshaft carrying the dialswitch blades.

6. The combination with a transformer having its primary winding dividedinto sections, of two dial switches having their clips connected toalternate sect-ions, a subdivided compensator having its terminalsconnected to the movable blades of said switches, contact bars connectedin between the divisions of the compensator, a carrier provided with aplurality of double ended fingers adapted to traverse said bars,- aplurality of collector strips in line with said fingers and makingcontact with one end thereof, means for moving said fingers over saidbars while the blades of the dial switches remain stationary, andconnected 95' means for shifting said blades when the fingers are ateither end of their travel.

7 The combination with a transformer having its primary winding dividedinto sections, of two dial switches having their clips connected toalternate sections, a subdivided compensator having its terminalsconnected to the movable blades of said switches, a common shaftactuating the blades of said switches, contact bars con- 105 nected inbetween the divisions of the compensator, a carrier provided with apluralit-y of double ended fingers adapted to traverse said bars, aplurality of col- .lect-or strips in li ne with said fingers and makingcontact with one end thereof, means for moving said fin ers over saidbars while the blades of the ial switches remain sta tionary, and anintermittent gearing connected to the shaft shifting said blades when 1the fingers are at either end of their -travel.

8: The combination with a transformer having its primary winding dividedinto sections, of dial switches for cutting-out sections, a compensatorfor gradually reducing the voltage of a section about to be cutout, acircuit breaker for opening the circuit through the compensator before adial switch operates, and means operating in synchronlsm with the dialswitches for act-uating said circuit breaker.

9. The combination with a transformer t having its primary windingdivided into sections, of two dial switches having their clips connectedto alterxlate sections, a subdivided compensator having its termlnaisconnected to the movable blades of said switches, contact bars connectedin between the divisions of the compensator, a plurality 'of doubleended fingers adapted to traverse said bars, a plurality of collectorstrips each having its own resistance in line with said fingers andmaking contact with one end thereof, means for moving said fingers oversaid bars While the blades of the dial switches remain stationary, andmeans for shifting said blades when the fingers are at Copies of thispatent may be obtained for my hand this 24th day of February, 1910.

F. GEHRKENS.

\Vitnesses Lnomn BENzINoEn, SAMUEL LoNosTRn-nr.

five cents each, by addressing the fiommissioner of Patents, Washington,D. C.

